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The first job was to improve the stiffness of the base frame.
I've added cross beams in the outer bay and in the centre under the main A frame have added two seperate beams that cross but do not touch.
The overall stiffness of the frame has increased significantly.
The valve is the next part of the project. I have an eccentric machined onto the main crank. This will have a slip ring machined to run on it. The valve itself is simple. The following diagram shows the valve slid to allow high pressure air to flow into the cylinder.
Note that the cylinder is connected to the centre port.
The valve is now shown slid across to allow the exhaust from the cylinder to flow out to atmosphere.
The valve has to move 9mm.
The valve was machined from 7/32quot; diameter steel.
This shows the valve block machined from brass with the hole through the centre reamed to 7/32".
The valve has a slot cut in the end and this will fit to a lever that will slide the valve.
There is quite a lot of finishing required on the valve block and I need to solder in the brass tubes connecting it to the air-in line, the cylinder and the exhaust pipe.
A nice way to mount the valve gear to the engine frame was to use some brass angle.
I cut the angle to length and then cut-down the lower angles to fit between the beams. This locates the valve nicely.
I machined 45° angles onto two pieces of square brass. I then clamped the two pieces together and drilled through the centre between them with an 8.5mm drill.
Then when I took the two pieces apart I machined a recess in one side to clear the hexagonal shape of the valve block.
This shows all of the parts balanced in place.
Note the orientation of the two support pieces and the orientation in the picture below with the parts soldered together - the finl orientation gave me a better fit and alignment.
I cleaned up the pieces and then clamped them all together on a piece of wood.
I then heated the pieces up with a large soldering iron - I left the heat on some time before applying a small amount of solder to the joints.
Still some cleaning up required, but getting there.
I ordered a globe valve, some 5/32" copper pipe and two double unions from SteamFittings.co.uk - great service, parts were delivered in under 2 days.
Will no have to make up a pipe bender so that I can get some nice crisp bends in the pipework.
If you have made a similar engine and would like to share your experience we would love to hear from you - ed.